Hello, I'm a bass player and someone recommended me this build. I did the search and every link is broken. I would like any information anyone can give me. It sounds promising and I'd like to know a little more. If anyone has sound samples, that'd be cool too.

Thanks
Conrad

The schematic and some samples are in this thread. http://www.diystompboxes.com/smfforum/index.php?topic=48815.0

I have been to that discussion, but most of the things Morula related are no longer there. The original hand-drawn schematic is still there, but I think someone tried to update it in there, and that is missing. None of the sound clips are there. If there are not clips, can anyone describe it for me?

Thanks again,
Conrad

Edit: I found the one sample that you hosted, Slacker. I think that there's an updated schematic that's missing, though.

Radamus,

the updated shcematic: http://www.aronnelson.com/gallery/main.php/v/Richard-Boop-RLBJR65/album107/Morula_Schematic.gif.html
vero layout: http://www.aronnelson.com/gallery/main.php/v/Richard-Boop-RLBJR65/album107/Morula_2.gif.html?g2_imageViewsIndex=1

tried to update it, never did it
will not promess anything, but this thing could be lot better, maybe i can put some hands at work

cheers

breadboarded it,
and i tell you_: its not worth it

this is why: it oscillated when i put it together, and it didn't back then, that means it depends on components tolerances, then it needs tune up.. a mess

pick some OTA based lo pass filter/band pass whatever, stick a LFO to it, and youll get a hell lot better autowah

thanks for the interest anyways

Inverters gain depend on the power supply voltage. So does the Q in this case. Try to vary it. Or connect a dampening pot from pin5 to 4 of 1M or more.

You'd suggest not to try it then?! What a pity...the sound clips were so good!!!

Recent thread: http://www.diystompboxes.com/smfforum/index.php?topic=73671.0

uh, didn't see this one...actually I've got a couple of 4049 lying around...THX Rick!!! 

I think that I will put this project into the realm of things I will breadboard. It doesn't look like the parts are going to break the bank, so I'll put them in the next order. I think I've made enough pedals that I can safely mod a little. Thanks for double checking everything. If nothing else, it'll be an experiment into inverter based filters.

ehh ..reading oldrocker's post, this circuit might be worth building 

for those interested in modding, if i don't do it too soon (for time, or even motivation), i thought of these:

-fixing/bettering the LFO input to the filter, so it thumps less (could be done optically)
-using the two spare inverters: one for another filter (paralell or series, your choice), and the other for inverting the LFO, so you get phase/anti-phase filtering, could be interesting to try it

cheers

Quote from: nordine on February 02, 2009, 04:30:06 AM
-fixing/bettering the LFO input to the filter, so it thumps less (could be done optically)
-using the two spare inverters: one for another filter (paralell or series, your choice), and the other for inverting the LFO, so you get phase/anti-phase filtering, could be interesting to try it

Didn't understand a word of that  . I haven't made anything with an LFO in it or inverter gates, so I'm not sure how well I'll be able to mod any of that. If you have any recommendations, I'm willing to do the work.

I posted this in one of the other topics about the Morula, but I'm looking for some help with the thumping. My new topic: http://www.diystompboxes.com/smfforum/index.php?topic=77530.0

Any help you can give me would be awesome. Thanks again for this cool project.

Conrad

hold on a bit, ill try some of these ideas this weekend, maybe something good can come out 

Quote from: nordine on July 03, 2009, 02:08:26 PM
hold on a bit, ill try some of these ideas this weekend, maybe something good can come out 

Hey, thanks a lot. By the way, if you give me the idea of what you think might help, I can possibly test it for you. I just don't really understand how the inverter stages work exactly, something like a push-pull amplifier if I remember that chapter, but I can do the work.

Hello,
I am resurrecting this thread (10 years !), because i just discovered this little autowah circuit, had a spare 4049, and built it.
The circuit works as expected, but there are a few tweaks and niggles here and there, and as there is very little informations about it on internet.

This is the schematic :

https://www.aronnelson.com/gallery/main.php/v/Richard-Boop-RLBJR65/album107/Morula_Schematic.gif.html

This is the two threads i have found talking about it :
https://www.diystompboxes.com/smfforum/index.php?topic=77530.0
https://www.diystompboxes.com/smfforum/index.php?topic=60006.0

This is the layout i have used to build it on veroboard :

https://www.aronnelson.com/gallery/main.php/v/Richard-Boop-RLBJR65/album107/Morula_2.gif.html?g2_imageViewsIndex=1

I have already made a little mod : a "color" pot (swapping the 100K (R4) for a 1M pot). It changes the sound a bit, and i enjoy it

- - -

Now, these are the little mods i would like to try, and asking for help :
My overall concern with Morula is that I find that most of the parameters are a bit on the "all or nothing" side (the pots nearly act as switches), so i would like to reach smoother transitions from one extreme value to another.

- First, I would like to be able to get slower RATES (but, if possible, keeping the fast rates as is).

- Then, I would like softer SWEEPS : the sweeping is a bit hard, choppy (not really a square wave, but something along these lines). Is there any way to reach a more progressive sweep (more like a triangle or sine wave) ?

- the DEPTH pot (as well as the "COLOR" pot i added) seem to have a "all or nothing" action, so i would like to find a solution to have smoother transitions from "doing nothing" to "full monty". So far, I have used linear pots : should i try log pots for a different feeling ? Or should I try a smaller value for the depth pot (at the moment it is 100K) ? Or should i try to tweak any other component in the circuit ?


I feel that this circuit is a nice one (i hard never seen any autowah using a 4049 !), it can sound great, but it is a bit of a sleeping beauty and i wish it could be slightly enhanced for even better performances

I'm not sure if that 100uF C6 was meant to be where it is placed in the circuit. Maybe that was supposed to be a power supply filter on pin1 of the 4049 to 0v? C7 should either be a non-polar type or x2 2.2uF in series with the positive plates outermost. Usually in this type of oscillator, C7 is THE timing capacitor and there is no C6 at all.

Thank you, AnotherJim.
So, it is quite an unusual way of connecting the chip ?
Do you think that changing C7 value (increasing it to 4.7µF, maybe ?) would change the RATE speed ?

Do you know what kind of LFO waveform does this chip outputs ? Can we have a softer shape for smoother sweeps ?

By the way, do you know what do C2 and C4 do in that circuit (i am trying to understand) ?

I am hearing some LFO thumping when no input signal is coming (it is not noticeable when i feed some music to the circuit) : is there any way to get rid of it ?

LFO thumping is because there is no power supply filtering. That is what the large 100uF might, I think, have been meant for. The LFO circuit using 3 inverters is a standard one. That big 100uF cap on the input is not standard.

The LFO waveform is a triangle out of inverter pin15. Triangle waves are common in this type of effect as they are usually close enough to a sine wave in effect. The inverter pin12 should have a square wave. Triangle and Square are often the basic choices in synthesisers for filter modulation.

The filter part works by forming a peak frequency response curve.
C2 removes upper frequencies from the negative feedback of the amplifier by diverting them down to 0v. This creates a treble boost starting fairly low down.
C4+C5 increase the negative feedback of the amplifier, reducing high frequencies but starting higher than C2 boosts them. Together with C2 action, they form a mid-range boost in response.

The LED works as a voltage-controlled resistor and varies the high frequency through C4+C5 by diverting some to 0v. As the LFO varies the LED resistance, the frequency response peak moves up and down giving the wah effect.

Thank you, that is a very good explanation, and it helps me understanding how the circuit works.

QuoteLFO thumping is because there is no power supply filtering.

How should I add good enough power supply filtering to kill the thump sound? By putting a 100R resistor in serie with a 100µF cap between +9V and Ground ?

QuoteThe LFO waveform is a triangle out

After playing further with the effect, i quite like the way it sound. Imho, it's mainly the depth knob (which behaves too much like a on/off switch), and the rate knob (which is a bit too fast) which aren't great, but once i will have managed to dial in a wider range of depth values, I think the LFO will be fine.
To get slower minimum speed, should I increase C7 ?

QuoteDEPTH

It's strange because it really behaves like a switch, with the effect either "very audible" or "silent", but not much in between. I just have to turn it a little bit to hear it nearly in full action. I may try with a LOG pot instead of a linear one, but i feel that something else might be tweaked to get better results. I will try to find a way to make it behave better.

QuoteThe LED works as a voltage-controlled resistor and varies the high frequency through C4+C5 by diverting some to 0v. As the LFO varies the LED resistance, the frequency response peak moves up and down giving the wah effect.

Ok, that makes sense.
I used a regular 5mm red led : would a different kind of led change anything (like increasing or decreasing the range, or reacting sooner or later, or having a slightly different waveshape, etc)?

QuoteThe filter part works by forming a peak frequency response curve.

Thank  you for the in-depth explanation. I have some capacitors on sockets, so i may try with different values, but so far it sounds good to me.
I like it even better with the 1M pot instead of R4 (100k) : it seems to increase the resonance, and make the effect more "colored" (I just need to limit both the min and max values of it, so it would stay in the 200k-950k range).